Process for producing mixed diaryl esters of ortho-phosphoric acid



Patented Oct. 20, 1951? UNITED STATES PATENT OFFICE PROCESS FOR PRODUCING MIXED DIARYL ESTERS OF ORTHO-PHOSPHORIC ACID Harry R. Gamrath, St. Louis, Mo., assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application April 14, 1950, Serial No. 156,035

Claims. (Cl. 260-461) wherein R1 represents an aliphatic radical and R2 and Rs represent dissimilar aryl radicals. The aliphatic radical in the compounds embraced by the above described general formula may be acyclic or alicyclic, saturated or unsaturated, substituted or unsubstituted. Thus, the aliphatic radical may contain one or more of the following illustrative, but not limitative,substituents: halogens, such as chlorine, bromine, iodine and fluorine; nitro groups; alkoxy groups, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, etc.; aryl groups, such as phenyl and naphthyl and substituted phenyl and substituted naphthyl, :etc. The number of carbon atoms in the aliphatic radical may be varied over a wide range, as for example, from 1 to 24 carbon atoms. The dissimilar aryl radicals, such as the phenyl and naphthyl radicals, in the compounds embraced by the above described general formula and included within the scope of this invention, may be unsubstituted or mono or poly substituted. Thus, the aryl radical may contain one or more of the following illustrative, but not limitative, substituent radicals in one or more positions on the ring: alkyl radicals, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, etc.; halogens, such as chlorine, bromine, iodine and fluorine; nitro groups; alkoxy groups, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, etc.

The phosphate esters prepared by the novel process of this invention are generally nearly colorless liquids having mild, pleasant odors. These new esters have exceptional utility a flexibilizing plasticizers for polyvinyl chloride compositions, imparting to the compositions the properties of flexibility at freezing temperatures, low volatility loss of plasticizer at higher temperatures and non-inflammability. Such polyvinyl chloride compositions are in part disclosed and claimed in my copending application Serial No. 752,830, filed June 5, 1947, while certain of these phosphate esters are disclosed and claimed as compounds, per se, in my copending application Serial No. 23,133, filed April 24, 1948. Be-

cause of their low pour points and very high autogeneous ignition temperatures and compatibility with paraflinic hydrocarbon oils, these phosphate esters may be combined with parafiinic hydrocarbon oils to prepare hydraulic and torque converter fluids of highly desirable characteristics. Moreover, these esters have a wide variety of other uses, such as film-forming addition agents for extreme pressure lubricants and as the liquid medium for filters for air conditioning systems. Moreover, certain of these esters have a wide variety of other uses, such as lubricants for mechanisms from delicate clock works to extreme pressure bearing surfaces.

In all of the above mentioned uses of the phosphate esters prepared by the novel process of this invention, it is to be emphasized that exceptional purity is required. For example, in their use as plasticizers for polyvinyl chloride, excessive quantities of the dialkyl derivatives decrease the permanence of the plasticizer in the plasticized composition. Excessive quantities of the triaryl derivative in such applications cause a decrease in the flexibility characteristics of the plasticized compositions. Moreover, such impurities cause substantial changes in the autogeneou ignition temperatures of these phosphate esters and also substantial changes in the viscosity of these esters, thereby seriously affecting their utility as hydraulic and torque converter fluids.

It is an object of this invention to provide an improved process for the production of certain ortho-phosphoric acid esters. It is a further object of this invention to provide an improved commercially feasible process for the production of certain ortho-phosphoric acid esters characterized by an exceptional degree of purity.

Moreover, it is another object of this invention to provide an improved commercially feasible process for the production of certain orthophosphoric acid esters wherein the simple reactions of the process produce esters of such a high degree of purity that further purification by fractionation of the ester is unnecessary. Still further objects will become apparent from a, description of the novel process of this invention.

Heretofore, based on the'prior art for preparing phosphate esters, the preparation of the phosphate esters of this invention would be attempted through a multiple step procedure; According to such a procedure, in excess of one mol of phenol would be reacted with one mol of phosphorus oxychloride. The resulting mass would then be fractionated to separate the monophenyl phosphoryl dichloride from the diphenyl phosphoryl chloride and neutral triphenyl phosphate ester which also formed in the reaction. The isolated monophenyl phosphoryl dichloride would then be reacted with a slight. excessw otanother phenol. Afterf'tlie "reaction was do n'plete, the; mass would again be fractionated to separate the diaryl phosphoryl monochloride from the neutral phosphate esters which also form ed. The diaryl phosphoryl monochloride' c ont' dis?" similar aryl groups and isolatd'ifom such'a reaction, would be obtained in a verylow yield due to the competing additional reactions". To com:- plete the operations, the diaryl phosphoryl monochloride would then be reacted with: an,aliph t alcohol, usually in an inert mediur'ii'siich a'sjb zene, to yield the alkyl diaryl phosphate contain: ing dissimilar aryl groups. charged, the yield of alkyl di(mixed phate would be extremelyilowi #Contrary 'to. what would... have been expected or predicted, it has now ,:be,en. foundthatifa 1.--molecular proportion; of a; phosphoryl. dichloe ride"having thegformola f a a O e -Le here n. R1. s an a ,in i ad a1@ s ea ted with lmixturewmutaiflne. p oximatel molecu a proportion ach. f. the alk l metal nal l n arth. et l salt 11 o s mi ar ph nols n. la u o s m h re-. p uced a substa tialgy eld-of a ompoun hav n the formu a aryl) phoswherein R is an aliphatic radical and R and R are; dissimilar ary l radicalsl This resultant phosphate ester thus formed in high yields may be recovered from the aqueous reactionmixture, wssheawan water and dilute alliali and de r a m 3 =1 1 m.-. The e t rv hu v b: t isofsuichadegreepI puritythat further purification fractionation is u n nece ss ary.

lfi dlab er in b etxaana ys s 1 1 he Ph se-ha st rs. rep ed: c ib d. bov shows that the esters are: made up of predomi: tl e alkvldilmixe arid hea hat sa On the basis of the art hQBlZOfOre known, it would f .r ediei .i att e ier.. a si 1 fi o the reaction of 1 mol of alkyl phosphorylf dichloride in the presence of 1 mol of an alk ali metal or alkaline earth metal arylate. (I) and jl mol oi an alkal i, metal or alkaline earth metal arylate (11), would be amixture containing three esters, alkyl dilaryl I) phosphate, alkyl larvl phosph te and a kyl di(ary1 I, ary phosphata fi the roactivitiesof the twoarylates wereessentially the same, the prediction would ei' hatfi e. te mass, w ul .c aina out ne: third mol of each oi the phosphate esters. It has beeLfound however,that according to the novel 4 7 process or ,this, invention, the ester, obtained consists of, substantially pure alkyl dilaryl I,.arv1 II) pho ha Theiollowingexamples are illustrative of the novel process oi this invention -e hu hew were? P r s l. M mie For t troatcsttjjpr 0 v un dslof, -eth Y -H hexyl'phenyl p-cresyl phosphate, 44.5 pounds of Based on" *POCl was maintained a't25 C. and the agitation continu'edforat. least. one hour during which time awacuum was gradually applied to the reaction vessel; to remove the hydrogen chloride which was evolved, until an absolute pressure of 50 n i llinletrs of mercury was reached. The reaction vessel now contained octyl phosphoryl dichloride and was ready for use in the next step which is a Schotten-Baumann reaction withithe sodium.arylates.

The. sodium arylatesv were prepared. by. charg inganironkettle. withiilA pounds of water, 28.6. pounds of phenol, 32.9 pounds of p-cresoland 49 pounds of 50% sodium. hydroxide in amanner and at such a rate as to maintain a solution temperature below 25 C.

The crude Z-ethylhexyl phenyl p-cresyl phos phate was produced by charging the 2-ethylhexyl phosphoryl dichloride to the above prepared aqueous solution of sodium p-cresylate and sodiuinphenateat such a rate as tomainta in a reaction temperaturebelow 3. C. After the addition of the octyl phosphoryl dichloride was complete, the stirring wascontinuedand the temperature allowed to rise to 20 C.- The agita' tion was then stopped and the mixture allowed to stand until an ester layerand an aqueous salt layer formed and'the crude ester was thereupon drawn 011- Purification was efiected by washing the ester with dilute aqueous sodiumhydro'xide' until-the phenolic bodies and partial esters were removed'l If. desi red,' the ester may be further purified and refined by a choice of a variety of techniques well; known to those familiar with the art of refining phosphate esters. The yieldof; 2- ethylhexylphenylp-cresyl phosphate from the above process, based on the POC13 charged, was, 92%.U H

The refined 2-ethylhexyl phenyl p-cresyl phosphateprepared in" the above manner had thefollowing -properties;

Sp, g 259 2590 1.0785. aerim egigss 0.1-; 1.15082; Color Nearly waterwhits are commonly encountered in commercial;

cresol.. "B'y' cornmercial cresol is meant the article of commerce designated commercial cresoli and including such compositions as are described by Field, Dempster and Tilson, Ind. Eng. Chem. .32, 489,495 (1940).

The final product,.when commercial cresol is. us e d .-as.the source of the cresyl substituent,- will be a mixture of monoalkyl phenyl o-cresyl phosphate, monoalkyl EXAMPLE H Z-ethylhercyl phenyl cresyl phosphate (using commercial cresol as the source of the cresyl substituent) A 100-pound quantity of 2-ethylhexyl phenyl cresyl phosphate was prepared in the exact manner described in the foregoing example for the preparation of 100 pounds of 2-ethylhexyl phenyl p-cresyl phosphate, with the exception that 32.9

pounds of a commercial cresol having the approximate analysis:

Percent Ortho cresol 2 Meta cresol 45 Para cresol and xylenols- 53 Sp. gr. 25/25 C 1.0749

Ref. index 25 C 1.5080

Color Nearly water white EXAMPLE III Lauryl phenyl cresyl phosphate 115.1 g. of P0013 were cooled with stirring to about C. in a closed glass reaction vessel. 139.5 g. of lauryl alcohol was cooled to approximately C. and added to the P0013 with continuous stirring and at a rate so as to maintain a reaction temperature of 20 C. The reaction mixture was agitated and the temperature slowly raised to 10 C. and maintained at that temperature for one hour following the addition of all the lauryl alcohol; thereafter, the temperature was raised to approximately C. and the stirring continued for another hour. The hydrogen chloride gas which was evolved from the reaction was continuously removed by means of applying a vacuum to the reaction vessel.

The reaction vessel now contained lauryl phosphoryl dichloride and was ready for use in the next step which is a Schotten-Baumann reaction with the sodium arylates.

The sodium arylates were prepared by reacting '74 g. of phenol, g. of cresol with 63 g. of NaOH dissolved in 265 cc. of H20 in such a manner and added at such a rate so as to maintain a solution temperature below 25 C. The solution of sodium phenate and sodium cresylate was cooled to 5 C. and the lauryl phosphoryl dichloride added to the solution of the sodium arylates at such a rate so as to maintain a reaction temperature below 5 C. After the addition of the f desired, the ester may. vbefurther purified and refined by a choice of a variety of technique well known to those familiar with the art ofrefining phosphate esters. The yield of lauryl phenyl cresyl phosphate, based-on the phosphorus oxychloride charged, was

EXAMPLE IV n-Hexyl phenyl cresyl phosphate n-Hexyl phosphoryl dichloride was prepared by adding 102.1 g. of n-hexanol, cooled to 10 C., to 153.4 g. of phosphorus oxychloride cooled to 10 C. with stirring and with cooling and at a rate so as to maintain a reaction temperature of 10-15 C. After all of the n-hexanol had been added to the reaction, the cooling means was removed and while the agitation was continued the reaction temperature was allowed to rise to room temperature. Thereafter the stirring was continued while the reaction was placed under vacuum (approximately 50 millimeters of mercury absolute) for 1 /2 hours to complete the reaction and to remove the hydrogen chloride gas which was evolved from the reaction. The product of the above reaction between n-hexanol and phosphorus oxychloride was nhexyl phosphoryl dichloride.

The n-hexyl phosphoryl dichloride was reacted with an aqueous solution of sodium arylates cooled to 3 C. and prepared by adding 113.5 g. of cresol and 98.8 g. of phenol to 500 cc. of water having dissolved therein 180.7 g. of 46.5% sodium hydroxide solution, at such a rate so as to maintain a reaction temperature of 3 C. to 5 C. After all of the n-hexyl phosphoryl dichloride had been added to the solution of sodium arylates, the cooling means was removed and the reaction temperature allowed to rise to 22 C. Thereafter, the reaction was carriedto completion by continuous agitation for 1%; hours. After the agitation was stopped, the reaction mixture separated into an ester layer and an aqueous layer, and the ester layer was then separated from the aqueous layer by decantation. The ester layer was given successive washes with 2% NaOH solution and water thereby removing any unreacted phenolic bodies and partial esters and reduced alkalinity of the mass until it is acid to phenolphthalein. The ester was then further refined in accordance with the usual methods well known to those skilled in the art of refining phosphate esters. The yield, based on phosphorus oxychloride, was 89.7%.

n-Hexyl phenyl cresyl phosphate prepared as just described had the following properties:

lauryl phosphoryl dichloride was complete, the" stirring was continued and the temperature allowed to rise to 20-25" C. The reaction mixture was then allowed to stand until an ester layer and an aqueous layer formed and the crude. ester EXAMPLE v m' ylhervyz phenyl cresyl phosphate I 3,5,5-trimethylhexanolwere cooled to 5 C; to

layer was separated from the aqueous layer by decantation.

Purification was eifected by washing the ester with dilute aqueous sodium hydroxide untilthe phenolic bodies and partial esters were removed.

10 C. and were added to the phosphorus oxychloride with continuous stirring and at a rate so asto maintain areaction-mass temperature of about 15 C. The reaction mixture was then agitated while the temperature pf the reaction mixture was allowed to come up to room temperature; thereafter, the stirring was continued. and h i wi mir u ewas la ed-under. a vacuum -chloride, as above prepared by the reaction of thetrimethyl substituted primary hexanol an'd the-"phosphorus ox ychloride; was added 'to the aqueous solution :of sodium I ar-ylates at such :a rate so to maintain a: :reaction temperature lilor-ide had been: added to the aqueous solution premium-amass; thereaction mixture was agitated for a p'eriod of three hours and allowed 'to "warm up' to room 'temperature. Whenzthe agitation wa's stopp'ed', the reaction mixture separated mt'o an ester layer and an aqueous layer and-the *ester' layer .Was then separated T from the aqueous layer: by: decantation; 'The ester layer= wasgiven successive washe with: 2 *NaOH solution theretrby removing the *unr'eacte'd :phenolic bodies and 'pattialiesters and reduoing the alkalinity of the mass until it was acid to phenolphthalein. The ieSterIWas-then further: refined in accordance with lthe." usualrmethods well known to those who are skilled iu the artsof refiningphosphate esters.-

.The yield basedron: phosphorus oxychloride. was -90.5f%'.

flutoxyethyt phenyl: cresyl' phosphate T5324" gear phosphorus oxychloride were cooled "withis'tirring to'ahout Ciin-a glass-lined closed reactionvessel. 118.1%."015 ethylene glycol monobutyl"etherwerercooled and added, with stirring, to thephosphorus-"oxychlori'deover a period of one hour-seas to maintain a reaction temperature'of about 16' (3; The'stirring'was continued *for 1'25 hours after the ethylene glycol monobutyl ethenha d been 'added; the temperature being maintainedat 15"C'.'to'-20- C. and the reaction -vesselbeing'heldunder-a vacuum ofabout 50 mm. at mercury "absolute to i remove the hydrogen chloride gas which was evolved from the. reaction. The reaction mass-was'substantially :butoxyethyl 'phosphoryl dichloride.

"The"butox'yet-hyl phosphoryl dichloride was added to' a cooled-aqueous solution consisting of 117.5 g. of sodium phenate, 136.5 g. of sodium cresyIateandGEO' ccvof water, over a periodof- 2 hours wh'ile" maintaining a reaction temperature 010 C. to 3 C. Thereafter, the temperature was allowed to rise to'20C. and thestirring con- "tinued'for an additional two. hours. Thereaetion' mixture'was then allowed to standuntil-en ester layenand an aqueous layer formed and the ester layer then decanted from the water layer. The crude ester was given successive washesWithflNaOHsolution and water to remove the: unreacted -phenolic bodies and-partial .-esters.and thereafter. refined in accordance with ltheiusua'l methodsknownto those -skilled-.;in the ..art-of. refininglphosphate esters. The yield. based on phosphorus -oxychloridepwas 89.1

z-methi lpehtozyethyl phenol. cresyl phosphate 153.4: g: ofzphosprous oxychloride were cooled -mith istir rlng to atone-10 0. ina glass-lined r-lclosed"reection='-vessel. 146' g. of-ethylene glycol 8 proximatelyflfi" 6: and adfiedi'to :the phosphorus oxychlorideawith continuous stirring-and-at a rate $0135 to maintain-a reactiontemperature of C. "'The reaction mixturewas agitated and -5 the reactiomtemperatureof 20"6. maintained for one hour following-the addition of all the ethylene. glycol mono-2-methylphentyl ether; itliereaft'er thetemperature =was=allowed-to rise "to approximately-" C. and the-stirring continued for another hour. The hydrogen chloride .gasiwhichawasievolvedifrom'th rea i wa anxiously-dammed:byqmeansrof applyinga vacurumtozthecreaotion.vessel.

After the; reaction between the ethylene glycol :-mono-z2-.-methylphentyl ether and the-phosphorus oxychloride sand the; removal ;of *the hydrogen chloride had been completed; ,the reaction mixaturelcontaining z-methylpentoxyethyl phosphoryl qdichloride was slowly added to a reactor contain- 2051112 an aqueous solution, cooled to about 0 :C.,

:the aqueous solution containing 117.5,g. ofsodium phenate and,136.5 g. of sodium cresylate. During'ithe'addition of the 2 -methylpentoxyethyl phosphoryl dichloride, the temperature was 25 -maintainedbelow 5 C. After the 2-methylpentoxyethyl phosphoryl dichloride had" been com- ;pletely'addedto the-- aqueous mixture of sodium arylates; with continuous stirring, the temperature-was-allowedto graduallyrise to -25" C.

Upon stopping the agitation; the reaction mixture soon separatediintoan aqueous -layer;andj--a crude ester layer. Theaqueous layerwasdrawn off and; discarded, andg the ester purified by washing with dilute aqueousNaOI-L until the phenolic o bodies and partial esters were removed. The

ester mayrbe-urther:purified-,,andrefined by a choiceqof avariety of techniqueswdlknown to those familiar withthe production of. phosphate esters.

The yield .of 2-methylpent0Xyethy1 phenyl re lfl q p te based n phosphorus oky lm ride, was about.80% I .EXAMPLE VIII z-ethgllhexomyethylphenyl cresyl phosphate Using the method of ExampleVII, ;l74.g.. of ethylene glycol mono-,Z -ethylhexyl ether Were substituted for thenleid g. of ethylene glycol mono- 2 methylpentyl ether. 2v ethylhexoxyethyl ph nylicresyl phosphat wasobtain d. i a yield of -90 hasedon phosphorus-Qxychloride, and

had-the following properties:

- .S p. .gr., 25725", .C 111 195 .Ref.,index 25 c 1.5020

EXAMPLE I-X Z-ethtllhexoxycthyl cresylgo-chlotophfinyl phosphate,

Usin theemethod;asdescribed in'BxampleJVII, 2rethylhexoxyethyl, .cresyl; zo chlorophenyl phosphatewas. made from-the; followina ingredients:

From :these charges-ofstarting materials, 403;?

15g. of ;phosphate ester were obtained; representing a yield of 88.8% on phosphorus 1 oxychloride. a'Bhysicial properties of'this ester were:

EXAMPLE X n-Decomycthyl phenyl cresyl phosphate To 200 g. of phosphorus oxychloride, cooled to about 20 C. in a closed and continuously cooled reactor, 264.5 g. of ethylene glycol monodecyl ether were added with stirring and at a rate so as to maintain a reaction temperature of about 20 C. After all of the ethylene glycol monodecyl ether had been added to the phosphorus oxychloride, the reaction mixture was agitated and the temperature slowly raised to and maintained at 25 C. to 30 C. for about one hour. Thereafter the temperature was raised to 40 C. and maintained at that temperature for an additional hour while the stirring was continued and a vacuum of 25 mm. of mercury absolute was applied to the reactor to remove the hydrogen chloride formed during the reaction. The product of this reaction was decoxyethyl phosphoryl dichloride.

A solution of sodium arylates, containing 178.2 g. of sodium cresylate and 153 g. of sodium phenate dissolved in 850 cc. of water, was cooled to C. and while the cooling of the aqueous solution of the sodium arylates was continued, the above prepared decoxyethyl phosphoryl dichloride was slowly added to the cooled solution of sodium arylates with stirring and at a rate so as to maintain a reaction temperature of about 5 'C. Thereafter, the temperature was slowly raised to 30 C. and the stirring continued for another hour, at which time the reaction was finished with the formation of decoxyethyl phenyl cresyl phosphate. When the stirring of the reaction mixture was stopped, the mixture separated into an aqueous layer and the crude ester layer. It is often desirable to add additional sodium chloride to the reaction mixture to aid in the salting out of the ester, as the alkoxyethyl phenyl cresyl phosphates having the longer alkyl substituents often times do not have a sharp water and ester layer separation. After separation of the crude ester from the reaction mixture, the ester was given successive washes with 2% NaOI-I solution and water, thereby removing the unreacted phenolic bodies and partial esters, and reducing th alkalinity of the mass until it is acid to phenolphthalein.

The yield of n-decoxyethyl phenyl cresyl phosphate, based on phosphorus oxychloride, was 84%.

EXAMPLE XI Z-n-propylheptmzyethyl phenyl cresyl phosphate 76.7 g. of phosphorus oxychloride were cooled to 15 C. in a glass-lined closed reaction vessel, and with continuous cooling of the reactor, 101 g. of ethylene glycol mono-2-n-propylheptyl ether were added with stirring to the phosphorus oxychloride at a rate so as to maintain a reaction temperature of 15 C. to 20 C. After all of the ethylene glycol mono-Z-n-propylheptyl ether had been added, the agitation was continued while the temperature was raised to about 25 C., at which time a vacuum of 25 millimeters of mercury (absolute pressure) was applied to the reactor and maintained for about two hours to remove the hydrogen chloride evolved and carry the reaction to completion to form 2-n-propylheptoxyethyl phosphoryl dichloride.

An aqueous solution of sodium arylates, prepared by adding 500 g. of cresol and 49.4 g. of phenol to an aqueous alkalin solution prepared by dissolving 89.6 g. of 46.5% soda lye in 300 cc. of water, was cooled to 0 C. and the 2-n-propylheptoxyethylphosphoryl dichloride was added to the cooled solution of sodium arylates with stirring and at a rate so as to maintain a reaction temperature of about 5 C. Thereafter, the reaction was finished off by slowly raising the temperature to about 25 C. and stirring for 2% to 3 hours. The finished ester was then recovered and purified in the manner described for the preparation of decoxyethyl phenyl cresyl phosphate.

The yield of 2-n-propylheptoxyethyl phenyl cresyl phosphate, based on phosphorus oxychloride, was 87.5

EXAMPLE XII Tridecyl phenyl cresyl phosphate 120.1 g. of a 13 carbon branched chain alcohol prepared from the polymerization products of olefins were cooled to about 20 C. and added to about 92.0 g. of POCIs cooled to about 20 C. in a lass lined closed reaction vessel with continuous stirring and cooling so as to maintain a reaction temperature of about 20 C. The reaction mixture was agitated and the temperature slowly raised to 30-40 C. and maintained at that tem perature for one hour following the addition of all the tridecyl alcohol. The temperature was then raised to about 50 C. and the stirring continued for another hour. The hydrogen chloride gas which was evolved from the reaction was continuously removed by means of applying a vacuum to the reaction vessel.

158.9 g. of the above prepared tridecyl phosphoryl dichloride were transferred to a reactor containing an aqueous solution of potassium phenate and potassium cresylate, at a temperature below 15 0., prepared from 150 cc. of water, 49.4 g. of phenol, 56.7 g. of cresol and 117 g. of a 50% potassium hydroxide. Th tridecyl phosphoryl dichloride was added to the sodium arylate solution at such a rate as to maintain a temperature between 11 and 14 C. After all the tridecyl phosphoryl dichloride had been added to the sodium arylate solution, the reaction was carried to completion. The reaction mixture was then allowed to stand until an ester layer and an aqueous layer formed and the ester layer was separated from the aqueous layer. The ester was given successive washes with a sodium hydroxide solution and water and then dehydrated under vacuum at about C. An excellent yield of tridecyl phenyl cresyl phosphate was obtained.

EXAMPLE XIII Octodecyl phenyl chloro-alpha-naphthyl phosphate The octadecyl alcohol used in this example was 2 (1,3,3 trimethylbutyl) 5,7,7 trimethyl 1- octanol prepared from the polymerization products of olefins.

76.7 g, of P0013 were cooled with stirring to about 25 C. in a glass-lined closed reaction vessel. 135.5 g. of the above described octadecyl alcohol were cooled and added to the P0013 at a rate so as to maintain a reaction temperature of about 25 C. The reaction mixture was continuously agitated and the temperature allowed to rise to room temperature, and maintained at this temperature for an additional one hour stirring period, during which time the hydrogen chloride gas evolved during the reaction was removed by means of applying a vacuum (below 30 mm. Hg absolute) to the reaction vessel.

The octadecyl phosphoryl dichloride was then transferred to a reactor containing an aqueous aces-p73 sodium arylate solution cooled to 25 C. and pre pared by adding 49.4 g. of phenol and 93.8 g. of chloro-alpha-naphthol to 250 cc. of water having dissolved therein 90.5 g. of 46.5% sodium hydroxide. The octadecyl phosphoryl dichloride was added to the aqueous sodium arylate solution at such a rate as to maintain a temperature below 30 C. After all of the octadecyl phosphoryl dichloride was added, the reaction mixture was stirred for an additional three hours, allowing the mixture to come to room temperature. On standing, the reaction mixture separated into an aqueous layer and an ester layer. The ester layer was removed and given successive washes with 2% sodium hydroxide solution and water, :and finally dehydrated under vacuum at about 110 C. The yield of octadecyl phenyl chloroalpha-naphthyl phosphate was excellent.

EXAMPLE XIV n-Tetradecoryethyl cresyl chlorocresyl phosphate 153.4 g. of POCh were cooled with stirring to about C. in a glass-lined closed reaction vessel. 258 g. of ethylene glycol mono-n-tetradecyl ether were cooled to approximately C. and added to the P0013 with continuous stirring and at a rate so as to maintain a reaction temperature of C. The reaction mixture was agitated and the reaction temperature of 20 C. mainous solution, cooled to about 0 C., and made up of 153.4 g. potassium cresylate and 189.6 g. potassium chlorocresylate. After all of the reactant had been added to the aqueous potassium arylate solution, the reaction mixture was agitated for 1%; hours and then with continuous stirring, the temperature was gradually raised to C. The reaction mixture was then allowed to stand until an ester layer and an aqueous layer had formed, and the ester layer was separated from the-aqueous layer. The ester was given successive washes with a sodium hydroxide solution and water, and then dehydrated under vacuum at about 110 0., thereby obtaining an excellent yield of n-tetradecoxyethyl cresyl chlorocresyl phosphate.

EXAMPLE XV Eicosyl phenyl 2,4-d2'chl0rophenyl phosphate In accordance with the procedure described in Example XIV, eicosyl phenyl 2,4-dichlorophenyl phosphate was prepared by reacting 41.5 g. of eicosyl phosphoryl dichloride with 11.6 g. of mag nesium phenate and 18.3 g. of magnesium 2,4- dichlorophenate contained in an aqueous medium. An excellent yield of ei-cosyl phenyl 2,4-dichlorophenyl phosphate was obtained.

EXAMPLE XVI Tetracosyl phenyl para-nitrophenyl phosphate In accordance with the procedure described in. Example XIV, an excellent yield of tetracosyl phenyl para-nitrophenyl phosphate was obtained by reacting 47 g. of tetracosyl phosphoryl dichloride with 11.3 g. of calcium phenate and 15.8 s.

12 of calcium para-nitrophenate contained in an aqueousmedium.

EXAMPLE XVII Beta-docosoasyethyl phenyl cresyl phosphate In accordance with the procedure described in Example XIV, an excellent yield of beta-decosoxyethyl phenyl cresyl phosphate was obtained by reacting 24.4 g. of beta-docosoxyethyl phosphoryl dichloride with an aqueous solution containing 7.0 g. of potassium phenate and 7.7 g. of potassium cresylate.

EXAMPLE XVIII Trimethylcyclohewyl para-nitrophenyl chlorocresyl phosphate In accordance with the procedure described in Example XIV, an excellent yield of trimethylcyclohexyl para-nitrophenyl chlorocresyl phosphate was obtained by reacting 259 g. of trimethylcyclohexyl phosphoryl dichloride with an aqueous solution containing 186 g. of potassium paranitrophenate and 189.6 g. of potassium chlorocresylate.

EXAMPLE XIX Perfluorobutyl phenyl cresyl phosphate In accordance with the procedure described in Example XIV, perfluorobutyl phenyl cresyl phosphate was prepared in an excellent yield by reacting 35.3 g. of periluorobutyl phosphoryl dichloride with an aqueous solution containing 12.2 g. of sodium phenate and 13.7 g. of sodium cresylate.

EXAMPLE XX Beta-phenoryethyl phenyl cresyl phosphate In accordance with the procedure described in Example XIV, an excellent yield of beta-phenoxyethyl phenyl cresyl phosphate was obtained by reacting 255 g. of beta-phenoxyethyl phosphoryl dichloride with an aqueous solution containing 138.6 g. of potassium phenate and 153.3 g. of potassium cresylate.

EXAMPLE XXI Methyl phenyl cresyl phosphate 368.2 g. of POCla were cooled with stirring to about 5 C. in a closed glass-lined reaction vessel. 64 g. of methyl alcohol were cooled and added to the POCla with continuous stirring and at a rate so as to maintain a reaction temperature of about 0 C. The reaction mixture was agitated and the temperatureslowly raised to about 25 C. and maintained at that temperature for one. hour following the addition of all the methyl alcohol. The hydrogen chloride gas which was evolved from the reaction was continuously removed by means of applying a reduced pressure to the reaction vessel.

After the removal of the hydrogen chloride was essentially complete, the mass was fractionated keeping the still pot temperature below C. The main fraction, methyl phosphoryl dichloride, was collected in the boiling range of 62-68" C./30 mm. absolute pressure (Hg). A yield of 88.2% on phosphorus oxychloride was obtained.

A solution of sodium arylates was prepared by reacting 98.7 g. of phenol, 113.4 g. of cresol with 173 g. of 48.6% sodium hydroxide dissolved in 300 cc. of water in such a manner and added at such a rate so as to maintain a solution temperature below 25 C. The solution of sodium phenate 13 and sodium cresylate was cooled to C. and then 149 g. of distilled methyl phosphoryl dichloride was added to the solution of the sodium arylates at such a rate so as to maintain a reaction temperature below 5 C. After the addition of the methyl phosphoryl dichloride was complete, the stirring was continued and the temperature allowed to rise to about 25 C. The reaction mixture was then allowed to stand until an ester layer and an aqueous layer formed and the crude ester layer was separated from the aqueous layer by decantation. Purification of the crude ester layer was effected by washing the ester with a dilute sodium hydroxide solution followed by washing with water. The ester was then dehydrated under a reduced pressure and an excellent yield of methyl phenyl cresyl phosphate obtained.

EXAMPLE XII Z-ethylbutyl phenyl cresyl phosphate In a manner similar to that used for the preparation of n-hexyl phenyl cresyl phosphate (Example IV), 2-ethylbutyl phenyl cresyl phosphate was prepared from the following reactants:

Phosphorus oxychloride g 153.4 z-ethylbutanol g 102.0 Phenol g 98.8 Cresol g 113.4 Sodium hydroxide g. (as 47.0%) 178.7 Water cc 280 From these charges, 324.6 g. of 2-ethy1buty1 phenyl cresyl phosphate were obtained. This represents a yield of 93.4% on phosphorus oxy- EXAMPLE XXIII Z-ethyZhemg Z phenyl chlorophenyl phosphate In accordance with the procedure described in Example XIV, 2-ethylhexyl phenyl chlorophenyl phosphate was prepared utilizing the following ingredients:

2-ethylhexanol g 130.1 Phosphorus oxychloride g 153.4 Phenol g 98.7 Chlorophenol g 134.9 Potassium hydroxide -g. (as l00%) 117.8 Vfater cc 300 EXAMPLE! XXIV fi-methylheptyl phenyl cresyl phosphate In accordance with the procedure described in Example XIV, fi-methylheptyl phenyl cresyl phosphate was prepared utilizing the following ingredients 6-methylheptanol g 130.1 Phosphorus oxychloride g 153.4 Phenol g 98.7 Cresol g 113.4 Potassium hydroxide g. (as 100%) 117.8 Water cc 300 An excellent yield of S-methylheptyl phenyl cresyl phosphate was obtained.

EXAMPLE XXV G-methylheptyl cresyl beta-naphthyl phosphate -14 in' Example XIV, 6-methylheptyl cresyl beta. naphthyl phosphate was prepared in good yield from the following starting materials:

G-methylheptanol g 65.0 Phosphorus oxychloride g 76.7 Oresol g 57.2 Beta-naphthol g 76.4 Sodium hydroxide g. (as 48.7%) 87.0 Water cc 300 The properties of this phosphate ester were:

Sp. gr. 25/25 C. 1.1162 Ref. index 25 C. 1.5588

Analysis g fgg Calculated for CzzsH31O4P 7. 26 Found 6.

EXAMPLE XXVI .6-methylheptyl cresyl o-nitrophem/l phosphate In accordance with the procedure described in Example XIV, G-methylheptyl cresyl o-nitrophenyl phosphate was prepared in good yield from the following starting materials:

fi-methylheptanol g 65.0 Phosphorus oxychloride g 76.7 C'resol g 57.2 o-Nitrophenol g 73.6 'Sodium hydroxide g. (as 48.7%) 87.0 Water cc 550 The properties of this phosphate ester were:

Sp. gr. 25/25 C. 1.1678 Ref. index 25 C. 1.5211

. Ph 11 N' Analyse ssh 1.1.5855? Calculated f0! CmHzaOcNP 7. 36 3. 33 Found 6. 84 3.58

In addition to the monoalkyl diaryl phosphate esters prepared in the preceding examples according to the novel process of this invention, the following esters are further illustrations, but not limitative, of esters which may be prepared in accordance with the process of this invention:

Ethyl phenyl cresyl phosphate n-Butyl phenyl cresyl phosphate 2-methylpentyl phenyl cresyl phosphate n-Octyl phenyl cresyl phosphate Nonyl phenyl cresyl phosphate Trimethylhexyl phenyl cresyl phosphate Decyl phenyl cresyl phosphate 2-n-propylheptyl phenyl cresyl phosphate Dodecyl phenyl cresyl phosphate 2-ethylbutoxyethyl phenyl cresyl phosphate n-Hexoxyethyl phenyl cresyl phosphate Octoxyethyl phenyl cresyl phosphate n-Octoxyethyl phenyl cresyl phosphate Iso-octoxyethyl phenyl cresyl phosphate Nonoxyethyl phenyl cresyl phosphate Trimethylhexoxyethyl phenyl cresyl phosphate Decoxyethyl phenyl cresyl phosphate Dodecoxyethyl phenyl cresyl phosphate Methyl o-chlorophenyl bromocresyl phosphate Ethyl 2,4-dibromophenyl chloronaphthyl phosphate Propyl p-chlorophenyl o-cresyl phosphate Butyl 2,4-dichlorophenyl p-ethylphenyl phos''-- phate In accordance with the procedure described 75 Isobutyl cresyl a-naphthyl phosphate Amyl p-.nitrophenyl bromonaphthyl phosphate Isoamyl io.-methoxphenyl .cre'sylphospha'te Allyl pentachlorophenyl 'fi-naphthyl phosphate Methallyl p-butoxyphenyl m-cresyl phosphate Nitrobutyl p-fi-uorophenyl chlorocresyl phosphate Nitroamyl 2,4,5-trichlorophehyl chloronaphthyl phosphate fl- Hydroxyethyl -o-chlorophenyl bromonaphthyl phospha'te ,o-Chloroethyl 2,4-dichlorophenyl p-cresyl phosphate Perfluorobutyl phen'yl bromocresyl phosphate Cyclohex-yl -p-nitropheny1 a-na-phthy-l phosphate Gyclopenty-l 2,4-dibromophenyl cresyl phosphate Trimethylcyclohexyl o-cresyl dichloronaphtlryl phosphate B-Phenoxyethyl pentachlorophenyl cresyl phosphate fl-Benzoxyethyl p-nitrophenyl o-iodophenyl phosphate Benzyl o-methoxyphenyl p-ethylphenyl phosphate Carbitol p-fiuoro'phenyl p-butoxyphenyl phosphate Eicosyl fl-naphthyl m-cresyl phosphate,

Docosyl p-butoxyphenyl chloronaphthyl phosphate I Tetracosyl o chlorophenyl "phosphatee Methoxyethyl p ni-trophenyl p butoxyphenyl phosphate Ethoxyethyl chlorocresyl dichloronaph-thyl phosphate Propoxethyl 2,4,5-trichlorophenyl m-cresyl phosphate Eicosoxyethyl phenyl p-ethylphenyl phosphate Tetracosoxyethyl 2.4;5-trichlorophenyl a-naphthyl phosphate Tridecyl 2,4-dibromophenyl chlorocresyl phosphate Tetradecyl chloronaphthyl o-iodophenyl phosphate Tetradecoxyethyl cres'yl p-fluorophenyl phosphate Pentadecyl chlorocresyl pentachlorophenyl phosphate Pentadecoxyethyl o-methoxyphenyl ,B-naphthyl phosphate Hexadecyl p-butoxyphenyl p-n-itrophenyl phosphate He xadecoxyethyl p-ethylphenyl p-cresyl phosphate I Octadecyl p-fiuorophenyl dichloronaphthyl phos-- phate Octadecoxyethyl phenyl bromohaphthyl phosphate Allyl phenyl cresyl phosphate Methallyl phenyl naphthyl phosphate Nitrobutyl chlorophenyl phenyl phosphate fi-Hydroxyethyl nitrophenyl cresyl phosphate B-Chloroethyl isopropylphenyl chloronaphthyl phosphate Cyclohexyl phenyl cresyl phosphate fl-Benzoxyethyl phenyl cresyl phosphate Carbitol phenyl cresyl phosphate Monoethyletlier of dieth'ylene glycol.

In the above list of compounds the nonyl and dodecyl radicals may be derived, in addition to the conventional sources, from the polymerization products of olefins, such as propylene or the do decyl radical may be derived from the polymerization products of olefins, such as butylene. These alkyl radicals may also be derived from branched chain primary alcohols prepared by the polymerization of olefins to form a branched dichloronaphthyl chain olefin, followed by the reaction with carbon monoxide and hydrogen (-oxo process) to form a primary branched chain alkyl alcohol. Thus, a nonyl alcohol may be prepared from the polymerization of isobutylene to form an octene which may then be reacted with carbon monoxide and hydrogen to form a branched chain primary nonyl alcohol. Nonaldehyde may be prepared in a similar manner and may then be subjected to an aldol condensation to form a branched chain primary octadecyl alcohol. The alkyl radicals may also be derived from straight chain primary alcohols obtained'by the hydrogenation of coconut oil and fats.

In the compounds of the invention, including those disclosed above, the cresyl radical may be ortho-cresyl, para-cresyl or 'meta-cresyl, for example, 2-ethylhexyl phenyl ortho-cre'syl phosphate, Z-ethylheiiyl phenyl para-cresyl phosphate, or 2-ethylhexyl phenyl meta-cresyl phosphate. Also, the products of the invention may comprise mixtures of phosphate esters containing ortho, para and/or me'ta-cresyl radicals.

While specific quantities, temperatures and reaction conditions have been set forth in the preceding examples, it is not intended that the novel process of this invention be restricted solely thereto; these quantities, temperatures and reaction conditions are subject to substantial variation. Thus, in the first step of the reaction, the particular phosphoryl dichloride which is an intermediate in the preparation of the phosphate esters prepared by the novel process of this invention, may be prepared any convenient man her which yields a substantially pure product. In the case of alkyl phosphoryl dichlorides wherein the alkyl substituent contains from 1 to 5 carbon atoms and alkoxyethyl phosphoryl dichlorides wherein the alkyl substituent contains from 1 to 3 carbon atoms, the alkyl phosphoryl dichloride may be formed by reacting substantially equimolecular proportions of P0013 and a primary alkyl alcohol containing from 1 to 5 carbon atoms or a beta-alkoxyethyl alcohol wherein the alkyl substituent contains from 1 to 3 carbon atoms or by reacting, if desired. a considerable excess of the appropriate alcohol with phosphorus oxychloride and subsequently recovering substantially pure alkyl phosphoryl dichloride by fractionation.

In the case of alkyl phosphoryl dichlorides wherein the alkyl substituent is an allryl radical terminating with a CH2 group and containing at least 6 and preferably from 6 to 2% carbon atoms or an alkoxyethyl radical wherein the alkyl substituent contains at least 4 and preferably from 4 to 24 carbon atoms, it is necessary that substantially equimolecular proportions of the primary alkyl alcohol or alkoxyetnyl alcohol and the POCls be utilized. In my copending application Serial No. 75,093, filed February 7, 1949, it was pointed out that monoalkyl phosphoryl dichlorides tend to decompose with the decomposition being dependent upon the length of the alkyl substituent and upon time and temperature. In the case of the lower alkyl phosphoryl dichlorides, such as the C1 to C5 alkyl phosphoryl dichlorides, the boiling points of the compositions are lower than their respective decomposition range over commercially practical subatmospheric pressures, thereby permitting purification of the monoalkyl phosphoryl dichlorides by fractionation. However, the decomposition temperature ranges of the monoalkyl pho'sphoryl dichlorides which are intermediate to the formation of the monoalkyl diaryl phosphate esters embraced by the preferred embodiment of the novel process of this invention, are lower than their respective boiling points that could be obtained under commercially feasible subatmospheric pressures, thus rendering purification of the intermediate monoalkyl phosphoryl dichlorides by commercial fractionation impossible. Furthermore, if purified intermediate alkyl phosphoryl dichlorides are obtained and subsequently reacted with hydroxy aryl compounds to form monoalkyl diaryl phosphates in much the same manner as triphenyl phosphate or tricresyl phosphate is made, the relatively high temperatures required to cause the reaction to proceed essentially quantitatively are again higher than the decomposition temperature ranges of the respective alkyl phosphoryl dichlorides and consequently decomposition again results.

Typical relationships that exist between the boiling point and the decomposition temperature range of various alkyl phosphoryl dichlorides are shown on the following table where- 1n:

Column A is the time required for the exothermic decomposition to start when the alkyl phosphoryl dichloride is maintained at 100-110 C.

Column B is the boiling range when the mass temperature is maintained at 70-80 C., which is a reasonably safe mass temperature in view of the exothermic decomposition characteristics.

is seen that commercial purification of these acid chlorides by fractionation is impossible. Before the boiling points of these materials could be reached, decomposition would have resulted as evidenced by the exothermic decomposition reaction and separation of the decomposition products into two distinct layers. In order to distill these materials, a vacuum higher than that could be obtained with commercially practical equipment would be necessary. Molecular distillation has also proven to be unsatisfactory for the purification of these alkyl phosphoryl di chlorides because of their highly corrosive nature and their tendency to gas.

Butoxyethyl phosphoryl dichlorides does not decompose in essentially the same manner as do the other derivatives, that is, an exothermic decomposition accompanied with a separation of the decomposition products, but on being subjected to heat, the butoxyethyl phosphoryl dichloride severely discolors, which coloration is evident in the final butoxyethyl diaryl phosphate. Thus, according to the methods heretofore practiced, the elevated temperatures used in the reaction of alkoxyethyl phosphoryl dichlorides with a hydroxy aryl compound would lead to highly colored monoalkoxyethyl diaryl phosphate esters which are not suitable for the applications previously mentioned.

Notwithstanding the foregoing remarks, a slight variation is permissible from the preferred equimolecular proportion of the alcohol and the POC13 utilized. However, as the molecular pro- Specific Gravity, Compound I25 G.

A B (mm. Hg absolute) Methyl phosphoryl dichloride Butyl phosphoryl dichloride. Isoamyl phosphoryl dichloride Butoxyethyl phosphoryl dichloride n-hexyl phosphoryl dichloride 1.0556 0.9995 at 31 25 Q-..

None in 24 hours 1.25l.5 hours minutes No separation in 13 hrs. Severely blackens in about 1-2 hours.

40-50 min Does not distill with mass temp. at 80 under 0.8 mm. pressure.

It is evident that methyl phosphoryl dichloride may be purified by fractionation inasmuch as no decomposition was found after 24 hours at C. and that its boiling point under 30 mm. vacuum, a commercially feasible pressure, is below its decomposition point. Butyl phosphoryl dichloride and isoamyl phosphoryl dichloride may similarly be fractionated as their boiling points at commercially feasible subatmospherio pressures may be reduced below their respective decomposition temperature ranges. However, it is evident that as the length of the alkyl chain is increased the tendency to decompose is also increased which is substantiated by considering the other mentioned alkyl phosphoryl dichlorides. Thus, it is evident from the extremely short decomposition time of the isoamyl phosphoryl chloride at l00-110 C. and the high vacuum necessary to reduce its boiling point so that it may be fractionated without decomposition, that a further increase in the length of the alkyl chain would render impossible puri-- fication of the alkyl phosphoryl dichloride by distillation. Considering the alkyl phosphoryl dichlorides which are intermediate to the formation of the monoalkyl diaryl phosphates prepared by the novel process of this invention, it

portion of the alcohol is increased beyond the preferred one molecular proportion, the formation of dialkyl phosphoryl chloride is promoted affecting the yield and quality of the final product. If the molecular proportion of the alcohol is reduced below the preferred one molecular proportion, the yield of the finished product is reduced due to the presence of unreacted phosphorus oxychloride which must beremoved by fractionation to prevent the formation of the triaryl derivative during the subsequent reaction.

Preferably, therefore, the alkyl and alkoxyethyl phosphoryl dichlorides utilized in preparing the alkyl diaryl phosphate esters according to the novel process of this invention are prepared by reacting equimolecular proportions of a primary alkyl alcohol containing from l to 24 carbon atoms or beta-alkoxyethyl alcohol wherein the alkyl su-bstituent contains from 1 to 24 carbon atoms and P0013. The reaction between the alcohol and phosphorus oxychloride is exothermic and is accompanied by a considerable evolution of hydrogen chloride. The rate of addition of the alcohol and the temperature at which the reaction mass is maintained is, therefore, governed by the nature of the equipment, cooling capacity and ability to remove hydrogen chloride 19 as it is formed to prevent too violent a reaction.

The practical temperature range limits of this reaction are governed by the freezing point of POCls and the color of finished product desired. Since POCls crystallizes at approximately 2 0., initial reaction temperatures below 2 C. are not practical. Once the reaction is begun, the tem-'- perature may then be reduced below +2 C. as the alcohol added and the alkyl phosphoryl di chloride formed depress the crystallizing point of the mass so that lower temperatures may be maintained. As the temperature of the reaction is increased greater than 25 C., the color of the monoalkyl phosphoryl dichloride is increased resulting in more highly colored monoalkyl diaryl phosphate esters. Thus, the preferred and practical temperature range of this reaction is from about 2 C. to about 25 C. After the reaction is substantially complete, the temperature may be increased to a maximum of about 50 C. to facilitate the removal of the hydrogen chloride gas evolved in the reaction.

It is also preferred that the alcohol be added to the POCla. While the reverse order of addition of reactants may be utilized, such a reverse order promotes the formation of the dialkyl phosphoryl chloride and trialkyl phosphate ester thereby affecting the purity of the final product.

The concentration of the alkali metal or alkaline earth metal arylates in the aqueous medium is not critical. Thus, the arylates may bepresent in complete solution, in suspension, or as a slurry with water. The aqueous medium may be composed of water per se or mixtures of water and ether inert solvents such as, benzene, petroleum ether, naphtha, etc. It is preferred that approximately a one molecular proportion of each of the two dissimilar alkali metal or alkaline earth metal arylates be present for each one molecular proportion of alkyl phosphoryl dichloride. A 5% excess of the arylates can be readily tolerated. If less than one molecular proportion of each of the arylates is utilized, the yield of the final prodbe more difiicult in that excessive quantities of the arylate will have to be removed from the final product. Any of the alkali metal or alkaline earth metal salts may be utilized, such as, sodium, potassium, lithium, calcium, magnesium, etc.

The temperature of the reaction between the arylate and the monoalkyl phosphoryl dichloride is maintained preferably between 0 and 25 (2.; however, the reaction may be carried out from about to about 50 C. If the temperature of the reaction is maintained at the higher level, the color of the final product is somewhat darker than would have resulted if the reaction had been carried out at 0 to 25 C.

In carrying out the reaction between the monoalkyl phosphoryl dichloride and the alkali metal or alkaline earth metal arylates, it is highly preferred that the monoalkyl phosphoryl dichloride be added to the aqueous medium containin the alkaline earth metal or alkali metal arylates in order to obtain a pure monoalkyl diaryl phosphate. Reversing the order of addition of the reactants generally leads to hydrolysis with subsequent low yields of the finished product and the formation of a considerable amount of impurities.

The esters prepared by the novel process of this invention are of such a degree of purity, as heretofore mentioned, that purification by fractionation is unnecessary. Usually all that is required is a simple water and alkali wash followed by dehydration under vacuum. At times, however, it may be necessary to subject some of the more difiicultly purified esters to a simple steaming procedure to remove the last trace of the alcohol or other volatiles. This steaming operation can then be followed by dehydration in the normal manner.

This application is a continuation in part of copending application Serial No. 75,098, filed Feb ruary 7, 1949, now U. S. Patent 2,504,121, issued April 18, 1950, which was a continuation-in-part of application Serial No. 38,194, filed July 12, 1948, now abandoned, which was a continuation-inpart of application Serial No. 720,310, filed Janu ary 4, 1947, now abandoned. This application is also a continuation-in-part of copending application Serial No. 23,133, filed April 24, 1948, which is a continuation-in-part of copending application Serial No. 752,830, filed June 5, 1947, now U. S. Patent 2,504,120, issued April 18, 1950. This application is also a ccntinuation-in-part of copending application Serial No. 84,762, filed March 31, 19 19, which is a division of copending application Serial No. 375, filed January .2, 1948, now U. S. Patent 2,557,091, issued June 19, 1951. This application is also a continuation-in-part of copending application Serial No. 135,311, filed December 27, 1949, which was a continuation-inpart of copending application Serial No. 75,098, filed February 7, 1949, now U. SjPatent 2,504,121, issued April 18, 1950, which was a continuationin-part of application Serial No. 38,194, filed July 12, 1948, now abandoned, which was a continuation-in-part of application Serial No. 720,310, filed January i, 1947, now abandoned.

What is claimed is:

1. In a process for the preparation of esters of ortho-phosphoric acid having the formula wherein R1 represents an aliphatic radical and R2 and R3 represent dissimilar aryl radicals, the steps comprising reacting in an aqueous medium a one molecular proportion of a phosphoryl dichloride having the formula wherein R1 represents an aliphatic radical, with a mixture containing approximately a one molecular proportion of each of two arylates containing dissimilar aryl groups, said arylates being selected from the group consisting of the alkali metal arylates and the alkaline earth metal arylates.

2. The process as described in claim 1 wherein the phosphoryl dichloride is methyl phosphoryl dichloride, and the two dissimilar aryl groups are phenyl and cresyl.

3. The process as described in claim 1 wherein the phosphoryl dichloride is 2-ethylbutyl phosphoryl dichloride, and the two dissimilar aryl groups are phenyl and cresyl.

4. The process as described in claim 1 wherein the phosphoryl dichloride is an octyl phosphoryl dichloride.

5. The process as described in claim 4 wherein the two dissimilar aryl groups are phenyl and cresyl.

6. The process as described in claim 5 where- 21 in the octyl phosphoryl dichloride is 2-ethy1- hexyl phosphoryl dichloride.

"I. The process as described in claim 4 wherein the two dissimilar aryl groups are phenyl and chlorophenyl.

' 8. The process as described in claim 7 wherein the octyl phosphoryl dichloride is Z-ethylhexyl phosphoryl dichloride.

9. The process as described in claim 1 wherein the phosphoryl dichloride is nonyl phosphoryl dichloride.

10. The process as described in claim 9 wherein the nonyl phosphoryl dichloride is 3,5,5-trimethylhexyl phosphoryl dichloride and the two dissimilar aryl groups are phenyl and cresyl.

11. In a process for the preparation of esters of ortho-phosphoric acid having the formula wherein R1 represents an aliphatic radical and R2 and R3 represent dissimilar aryl radicals, the steps comprising reacting a one molecular proportion of POCh with approximately a one molecular proportion of a primary aliphatic alcohol while removing the hydrogen chloride formed and thereby forming a substantially pure phosphoryl dichloride having the formula wherein R1 represents an aliphatic radical, reacting in an aqueous medium the phosphoryl dichloride thus formed with a mixture containing approximately a one molecular proportion of each of two arylates containing dissimilar aryl groups, said arylates being selected from the 22 group consisting of the alkali metal arylates and the alkaline earth metal arylates' 12. The process as described in claim 11 wherein the primary aliphatic alcohol is methyl alcohol and the two dissimilar aryl groups are phenyl and cresyl.

13. The process as described in claim 11 wherein the primary aliphatic alcohol is 2-ethyl butanol and the two dissimilar aryl groups are phenyl and cresyl.

14. The process as described in claim 11 wherein the primary aliphatic alcohol is an octyl alcohol.

15. The process as described in claim 14 wherein the two dissimilar aryl groups are phenyl and cresyl.

16. The process as described in claim 15 wherein the octyl alcohol is 2-ethylhexanol.

17. The process as described in claim 14 wherein the two dissimilar aryl groups are phenyl and chlorophenyl.

18. The process as described in claim 17 References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,005,619 Graves June 18, 1935 2,225,285 Moyle Dec. 17, 1940 2,504,121 Gamrath Apr. 18, 1950 2,520,393 Fletcher Aug. 29, 1950 2,542,604 Weisei Feb. 20, 1951 

1. IN A PROCESS FOR THE PREPARATING OF ESTERS OF ORTHO-PHOSPHORIC ACID HAVING THE FORMULA 